Decoding method and apparatus in wireless communication system
The present disclosure relates to a 5G or pre-5G communication system for supporting a higher data transmission rate beyond the 4G communication system such as LTE. A decoding method using a polar code according to an embodiment of the present disclosure comprises the steps of: determining a first function for decoding input bits and a second function, which is independent from a log likelihood ratio (LLR) value of a previous input bit by the first function; and decoding the input bits in parallel using the first function and the second function. Also, the method comprises the steps of: determining an internal frozen bit using at least one input frozen bit which has a predetermined value of a predetermined position from among the input bits; and determining LLR values for layer bits sequentially from the higher layers of N layers.
1. A decoding method of an electronic device in a communication system, the method comprising:
receiving a signal including codeword bits that are encoded based on one polar code; and
decoding, in parallel, the codeword bits based on a first scheme and a second scheme to estimate information bits that correspond to the codeword bits,
wherein, in the second scheme, a second codeword bit is decoded independently from a log likelihood ratio (LLR) value of a first codeword bit which is obtained in the first scheme,
wherein the first codeword bit and the second codeword bit are included in the codeword bits, and the first codeword bit precedes the second codeword bit;
generating data according to the decoded codeword bits; and
transmitting a response signal based on the generated data in the communication system.
2. The decoding method of claim 1 , wherein the decoding includes, in case that a length of the codeword bits is 2 N , sequentially obtaining LLR values for bits included in each of N layers.
3. The decoding method of claim 2 , wherein the decoding includes:
identifying a value of an internal frozen bit based on at least one codeword frozen bit having a set value in a set position among the codeword bits, and
obtaining the LLR values for the bits of a layer sequentially from higher layers among the N layers.
4. The decoding method of claim 3 , wherein the identified value of the internal frozen bit and resultant values sequentially decoded per layer are stored in a memory.
5. The decoding method of claim 2 , wherein:
an LLR value of a first input bit in a first layer is obtained by an LLR value of a second input bit in second layer preceding the first layer in case that the first input bit is an information bit, and
the LLR value of the first input bit in the first layer is obtained by the LLR value of the second input bit in the second layer and a value of a frozen bit in case that the first input bit is the frozen bit.
6. The decoding method of claim 1 , wherein a number of the codeword bits to be decoded in parallel is identified based on a memory capacity necessary upon decoding and latency upon decoding.
7. The decoding method of claim 1 , wherein:
the first scheme is an equation below,
L
u
1
=
log
W
-
(
y
1
,
y
2
|
u
1
=
0
)
W
-
(
y
1
,
y
2
1
u
1
=
1
)
=
log
(
W
(
y
1
|
0
)
W
(
y
2
|
0
)
+
W
(
y
1
|
1
)
W
(
y
2
|
1
)
)
(
W
(
y
1
|
1
)
W
(
y
2
|
0
)
+
W
(
y
1
|
0
)
W
(
y
2
|
1
)
)
=
2
tanh
-
1
(
tanh
(
L
x
1
/
2
)
tanh
(
L
x
2
/
2
)
)
≈
sgn
(
L
x
1
)
sgn
(
L
x
2
)
min
{
L
x
1
,
L
x
2
}
≡
f
(
L
x
1
,
L
x
2
)
the second scheme is an equation below,
L
u
2
=
(
-
1
)
u
^
1
·
L
x
1
+
L
x
2
=
{
sgn
(
L
x
1
)
·
(
L
x
1
+
L
x
2
)
where
u
1
is
information
bit
sgn
(
L
x
1
+
L
x
2
)
·
L
x
1
+
L
x
2
where
u
1
is
frozen
bit
and
is
0
sgn
(
-
L
x
1
+
L
x
2
)
·
-
L
x
1
+
L
x
2
where
u
1
is
frozen
bit
and
is
1
≡
g
′
(
L
x
1
,
L
x
2
)
L u1 is an LLR value of the first codeword bit of a first layer,
L u2 is an LLR value of the second codeword bit of the first layer,
L x1 is a first input value of the first layer, and
L x2 is a second input value of the first layer.
8. An electronic device configured to perform decoding using a polar code in a communication system, the electronic device comprising:
a transceiver configured to receive a signal including codeword bits that are encoded based on one polar code; and
a decoder configured to:
decode, in parallel, the codeword bits based on a first scheme and a second scheme to estimate information bits that correspond to the codeword bits, wherein, in the second scheme, a second codeword bit is decoded independently from a log likelihood ratio (LLR) value of a first codeword bit which is obtained in the first scheme, and wherein the first codeword bit and the second codeword bit are included in the codeword bits, and the first codeword bit precedes the second codeword bit, and
generate data according to the decoded codeword bits; and
transmit, via the transceiver, a response signal based on the generated data in the communication system.
9. The electronic device of claim 8 , wherein the decoder is configured to, in case that a length of the codeword bits is 2 N , sequentially obtain LLR values for bits included in each of N layers.
10. The electronic device of claim 9 , wherein the decoder is configured to:
identify an internal frozen bit based on at least one codeword frozen bit having a set value in a set position among the codeword bits, and
obtain the LLR values for the bits of a layer sequentially from higher layers among the N layers.
11. The electronic device of claim 10 , further comprising a memory configured to store the identified value of the internal frozen bit and resultant values sequentially decoded per layer.
12. The electronic device of claim 9 , wherein:
an LLR value of a first input bit in a first layer is obtained by an LLR value of a second input bit in a second layer preceding the first layer in case that the first input bit is an information bit, and
the LLR value of the first input bit in the first layer is obtained by the LLR value of the second input bit in the second layer and a value of a frozen bit in case that the first input bit is the frozen bit.
13. The electronic device of claim 8 , wherein a number of the codeword bits to be decoded in parallel is identified based on a memory capacity necessary upon decoding and latency upon decoding.
14. The electronic device of claim 8 , wherein:
the first scheme is an equation below,
L
u
1
=
log
W
-
(
y
1
,
y
2
|
u
1
=
0
)
W
-
(
y
1
,
y
2
1
u
1
=
1
)
=
log
(
W
(
y
1
|
0
)
W
(
y
2
|
0
)
+
W
(
y
1
|
1
)
W
(
y
2
|
1
)
)
(
W
(
y
1
|
1
)
W
(
y
2
|
0
)
+
W
(
y
1
|
0
)
W
(
y
2
|
1
)
)
=
2
tanh
-
1
(
tanh
(
L
x
1
/
2
)
tanh
(
L
x
2
/
2
)
)
≈
sgn
(
L
x
1
)
sgn
(
L
x
2
)
min
{
L
x
1
,
L
x
2
}
≡
f
(
L
x
1
,
L
x
2
)
the second scheme is an equation below,
L
u
2
=
(
-
1
)
u
^
1
·
L
x
1
+
L
x
2
=
{
sgn
(
L
x
1
)
·
(
L
x
1
+
L
x
2
)
where
u
1
is
information
bit
sgn
(
L
x
1
+
L
x
2
)
·
L
x
1
+
L
x
2
where
u
1
is
frozen
bit
and
is
0
sgn
(
-
L
x
1
+
L
x
2
)
·
-
L
x
1
+
L
x
2
where
u
1
is
frozen
bit
and
is
1
≡
g
′
(
L
x
1
,
L
x
2
)
L u1 is an LLR value of the first codeword bit of a first layer,
L u2 is an LLR value of the second codeword bit of the first layer,
L x1 is a first input value of the first layer, and
L x2 is a second input value of the first layer.